1. Field of the Invention
This invention relates to an optical temperature sensor and to an associated fiber optic transmission system, which sensor employs birefringent crystals, the outputs of which can be decoded to provide a digital representation of temperature.
2. Prior Art
Few temperature sensors are known which are compatible with a fiber optic transmission system, which sensor and transmission system are remote from a central computing apparatus. Therefore, the prior art temperature sensors are not compatible with digital systems, whereby a digitally encoded output signal could be obtained from an optical input signal. However, an example of a temperature sensor that is adapted to be interfaced with a fiber optic transmission system to provide accurate digital representations of temperature can be found in U.S. Application Ser. No. 928,223 entitled FIBER OPTIC TEMPERATURE SENSOR, filed July 26, 1978.
More particularly, conventional temperature sensors supply analog representations of a temperature signal. Consequently, should a digital representation of an output signal be desired, relatively expensive and space consuming analog-to-digital equipment is required. Moreover, such conventional temperature sensors are limited in application, because of their inherently large size and slow response time. What is more, either complex transmission lines or signal conversion apparatus is typically required when the temperature sensor must collect information from a remote sample. Hence, prior art transmission systems that have heretofore been interfaced with temperature sensors of the prior art are relatively expensive to fabricate, are not capable for carrying sufficiently wide bandwidth signals, lack immunity to electro-magnetic and/or electro-static interferences, and require numerous interfacing apparatus.